Herbicidal method



United States Patent 3,174,842 HERBICIDAL METHOD Stanley R. McLane, Prospectville, John Russell Bishop, Hatfield, and Harvey 1. Raman, Philadelphia, Pa., assignors to Amchem Products, Inc., Ambler, Pa., a corporation of Delaware No Drawing. Original application Oct. 15, 1958, Ser. No. 767,292, now Patent No. 3,014,063, dated Dec. 19, 1961. Divided and this application Sept. 6, 1961, Ser.

7 Claims. (c1. 71-2.6)

This invention relates to new compositions of matter, and it more particularly relates to new compounds having herbicidal properties.

The present invention is exemplified by 3-amino-2,5- dichlorobenzoic acid and its functional derivatives having the general formula:

O I HQ c a'l wherein A may be Cl, OH, OH.M, NH or OX; M being either an amine selected from the group consisting of mono-, diand tri-straight or branched chain alkyl amines of from 1 to- 12 carbon atoms or an alkanol amine such as mono-, dior tri-alkanol amine having from 2 to 9 total carbon atoms; and X being either an ammonium radical or an alkali metal ion such as sodium or potassium.

The aforementioned acid as well as the aforementioned functional derivatives thereof, such as the alkali metal and ammonium salts and the amines and amides, have a highly desirable selective herbicidal activity.

Preparations of the 3-amino-2,S-dichlorobenzoic acid as well as some of the functional derivatives thereof are indicated by way of example in a non-limitative manner as follows:

EXAMPLE I 23.6 grams (0.1 mole) of pure 3-nitro-2,5-dichlorobenzoic acid (M.P. 22022l C.) and 20 grams (0.169 mole) of granular tin are admixed in a flask to which is then added 100 milliliters of water and 100 milliliters of concentrated hydrochloric acid. The flask is then heated to 90100 C., this temperature being thereafter maintained until complete solution takes place (usually about 6 hours).

After complete solution has occurred, the entire solution is poured into a mixture of 1000 mls. of water and ice, whereby a crude precipitate is formed. This precipitate is collected and reslurried in 1000 mls. of water to remove any inorganic salt contaminants. The crude precipitate is then recrystallized from boiling water (solubility 6 grams/100 mls.) and dried in an oven at 100 C. A white crystalline product is recovered in about an 80% yield based upon the 3-nitno-2,5-dichlorobenzoic acid; this product being 3-amino-2,5-dichlorobenzo-ic acid.

The white crystalline product is analyzed as follows:

Melting point: 200-201" C.

Chlorine: Calculated, percent34.4; found-34.4.

Nitrogen: Calculated, percent-6.8; found6.73.

Solubility (gm./100 gm. 25 C.): Water0.0007;

ethyl alcohol-17.28; i-propyl alcohol--12.69.

EXAMPLE II 20.6 grams (0.1 mole) 3-amino-2,5-dichlorobenzoic acid are dissolved in 100 mls. of methyl alcohol. This mixture is added to a solution containing 5.7 grams (0.1 mole) of sodium methylate dissolved in mls. of methanol. The mixture is then evaporated to 25 mls. on a steam bath. The resulting concentrate is cooled and the precipitated crude sodium salt is recovered by filtration. The crude salt is then purified by recrystallization from methyl alcohol and is then filtered and dried.

Solubility determinations on the sodium salt (based on gm./100 gm. 25 C.) were: Water15.75; ethyl alcohol8.97; i-propyl alcohol-4.70.

EXAMPLE III Melting point: 194197 C. (decomposed).

Solubility (gm/1'00 gm. 25 C.): Water-29.60;

ethyl alcohol-6.90; i-propyl alcoholl.655.

EXAMPLE IV 20.6 grams (0.1 mole) of pure 3-arnino2,5-dichlorobenzoic acid (M.P. 200201 C.) are placed in a ml. flask with a condenser. 37 grams (0.3 mole) of thionyl chloride are added and the mixture is refluxed on a steam bath for 6 hours. Excess thionyl chloride is removed by atmospheric distillation over a steam bath and complete removal is accomplished under reduced or subatmospheric pressure. The residue is crude 3-amino2,5-dichlorobenzoyl chloride.

The preparation is illustrated by the following reaction:

0 O ill-OH il-Cl EXAMPLE V 200 mls. of toluene are added to the crude 3-amino- 2,5-dichlorobenzoyl chloride obtained in the manner of Example IV. Anhydrous ammonia gas is sparged or sprayed for 30 minutes through the mixture at a temperature of 20-30 C. Thereafter, the reaction product is filtered to recover the precipitated crude product. The crude product is then washed with toluene and dried in an oven. It is then crystallized from boiling water.

The white crystalline product, 3-amino-2,5-dichlorobenzamide, which results from this process is analyzed as follows:

Melting point: 162163 C.

Chlorine: Calculated, percent-64.0; found, percent (Parr bomb)34.0.

Solubility (gm/100 gm. 26 C.): Water0.32; ethyl alcohol-11.06; i-propyl alcohol-7.62.

+ SO; HCl

The preparation of this 3-amino-2,5-dichlorobenzamide is a two stage synthesis whereby the first stage comprises the reaction illustrated in Example IV and the second stage is as follows:

The following table illustrates the high degree of selective herbicidal activity of a 3-amino-2,5-dichlorobenzoic compound. This compound was applied in pre-ernergence tests at the rate of 8 lbs/acre of acid equivalent.

Visual observations were recorded 17 days after applicatlon:

Table Test Plant Visual Observations Using 3- Amino-2,5-Dichlorobenzoic Acid Wheat No observable injury. Corn Do. Onion Sets Do. Snapbeans No injury to very slight injury. Soybeans Do. Wild Oats. Moderate injury. Foxtail.. Total kill. Ryegrass Severe injury. Grabgrass Johnson Grass Severe injury. Dock"; Do. Mustard Total kill. Pigweed Do. Lambs-Quarter Do. Chickweed Do.

The compounds of this invention may be applied as both preand post-emergence herbicides according to well established practices in the art wherein herbicidally effective amounts of the herbicides are admixed with a herbicidally inert carrier.

This application is a divisional of application Serial No. 767,292, filed October 15, 1958, now United States Patent No. 3,014,063.

What is claimed as the invention is:

1. A method of herbicidally controlling vegetation which comprises applying to the vegetation a herbicidally effective amount of a compound of the formula:

wherein A is a member of the group consisting of OH, OH.M, NH and OX; M being anamine selected from the group consisting of straight and branched chain alkyl amines having from 1 to 12 carbon atoms; and X being selected from the group consisting of ammoium ion, sodium ion and potassium ion.

2. The method of claim 1 wherein said compound is sodium salt of 3-amino2,S-dichlorobenzoic acid.

3. The method of claim 1 wherein said compound is potassium salt of 3-amino-2,S-dichlorobenzoic acid.

4. The method of claim 1 wherein said compound is ammonium salt of 3-an1ino-2,5-dichlorobenzoic acid.

5. The method of claim 1 wherein said compound is 3-amino-2,5-dichlorobenzoic acid.

6. The method of claim 1 wherein said compound is applied as a pro-emergent herbicide.

7. The method of claim 1 wherein said compound is applied as a post-emergent herbicide.

References Cited in the file of this patent UNITED STATES PATENTS Jones Feb. 12, 1946 Hart et al. Dec. 19, 1961 OTHER REFERENCES 

1. A METHOD OF HERBICIDALLY CONTROLLING VEGETATION WHICH COMPRISES APPLYING TO THE VEGETATION A HERBICIDALLY EFFECTIVE AMOUNT OF A COMPOUND OF THE FORMULA: 